The invention relates to a semiconductor switching device for guiding and amplifying electromagnetic radiation, having a semiconductor body with a substantially flat surface comprising a substrate region which is provided with a connection conductor, and a number of strip-shaped radiation guiding members which comprise a layer structure having an active layer in which the radiation propagates and having a p-n junction in which, for amplification of the radiation, each radiation guiding member is provided at the surface with at least an electrode to control a current in the forward direction through the p-n junction, one or more first radiation guiding members branching into at least two further radiation guiding members which over the greater part of their length are situated outside each other's amplification profile.
A prior art semiconductor switching device as described above is disclosed in U.S. Pat. No. 3,465,159.
In this known device the radiation guiding members comprise layer structures the extension of which, inclusive the active layer in which the radiation propagates, is restricted to the width of the radiation guiding members. The radiation guiding in this device in the direction of width is substantially refractive index guiding. This occurs due to a variation of the effective refractive index for the relevant radiation in the active layer in the direction of width of the radiation guiding member. This variation is caused by doping variations of the layer structure in the direction of width of the radiation guiding member, either in the active layer or in the adjoining layers.
One of the disadvantages of the device described is that, due to the substantially complete separation of the amplification profiles of the radiation guiding members, when using two or more first guiding members each branching into a further guiding member, the radiation in a "first" guiding member which branches into a nonactivated "further" guiding member is lost for the radiation guiding. In the activated "further" radiation guiding member(s), therefore, at most only a part of the radiation energy transported by the "first" guiding members will land. This may be an important disadvantage in integrated optical semiconductor switching devices in which the signal strength is generally comparatively small.
Furthermore, the transverse dimensions in known semiconductor switching devices, that is to say the width and the thickness of the radiation guiding members, are so large that guiding of several transverse modes of oscillation is possible. This is undesired in many cases. Transverse modes of oscillation are to be understood to mean herein modes of oscillation both in the direction of width and in the direction of thickness of the radiation guiding member.